How can you ban “aborting” embryos that are in the womb but support IVF which results in way more “aborted” embryos.

The exact way they are doing here: insist that they're somehow different and avoid thinking about the logical result of their beliefs in order to escape cognitive dissonance.

You may be overestimating how familiar they are with the specifics of IVF. It could be perceived as simply as "IVF means more babies, which is good, because I want babies. But abortion means less babies, which is bad."

If those people like that perception, they will resist or deny any further detail that would jeopardize those perceptions to remain willfully ignorant, especially if they have utilized IVF themselves. The cognitive dissonance would be too strong otherwise.

Feels like an old variant on the trolley problem.

I'd guess their view is something like, with an abortion, if you don't, there's a baby, but with an unimplanted embryo, if you do nothing there's no baby. Essentially absolving people for not taking an action, even though the outcome is the same as those they condemn when an action is taken in a similar situation. But it's also weird and telling how they're now arguing that just having more babies be born is some kind of implicit positive.

They don't see mental gymnastics as a problem in my experience. They make all these rules for how everyone should live and then naturally it sucks if you actually comply 100%, so they find ways to make the things they want ok (usually only for them though). They want babies, so actually it's totally fine to dispose of unused embryos. See also: modesty standards, gender roles, social programs, and so on.

I’ve always thought christian/catholic doctrine, if it really takes each potential life seriously, should require everyone to constantly procreate with anyone and everyone in order to instantiate each potential life.